Floating Tree WTF?

Hey, Guys! Today I created a new world on MC, with the seed: longliveherobrine. I walked a bit and found a tree. But, It was floating! I got scared, so I saved and quited. I imediatly thought: HEROBRINE! I swear I didn't chopped the tree! In the same world, I had another weird experience. I punched a log, It disapeared, and It reappeared, and then disapeared again! Another weird thing. I found a ravine. I got close to It, but I was always pressing Shift, so I didn't fall. Then, I fell while I was holding Shift!

I got scared and quited. I didn't deleted the world. Now, Herobrine roams around, looking for the next victim...He's watching you...